1. Field of the Invention
The present invention relates to systems for removing fluids from the subdural region of a patient and more particularly pertains to a new subdural evacuating port system for removing subdural fluid accumulations in a manner that is minimally invasive and promotes decompression, expansion, and recovery of the brain.
2. Description of the Prior Art
The subdural space of the human head is the space located between the brain and the lining of the brain, which is referred to as the dura mater (hereinafter referred to as the “dura”). Hemorrhages on the surface of the brain, for example, may cause a condition known as a subdural hematoma. The subdural hemorrhages may have a number of causes. For example, elderly persons may be more susceptible to subdural hemorrhages because as the brain ages it tends to become atrophic and the subdural space between the brain and the dura gradually enlarges. Bridging veins between brain and dura frequently stretch and rupture as a consequence of relatively minor head injuries, thus giving rise to a collection of blood in the subdural space. Further, severe linear deceleration of the brain can result in the brain moving excessively with respect to the dura, often causing rupture of the bridging veins or the blood vessels on the surface of the brain, which can in turn cause subdural hemorrhages in the “normal”, young, and otherwise healthy brain.
These subdural blood collections can be classified as acute subdural hematomas, subacute subdural hematomas, and chronic subdural hematomas. Acute subdural hematomas, which are associated with major cerebral trauma, generally consist primarily of fresh blood. Subacute subdural hematomas are generally associated with less severe injuries than those underlying the acute subdural hematomas. Chronic subdural hematomas are generally associated with even less severe, or relatively minor, injuries. The chronic subdural hematomas tend to be less dense liquid consisting of very diluted blood.
Another condition involving a subdural collection of fluid is a hygroma, which is a collection of cerebrospinal fluid (sometimes mixed with blood) beneath the dura, usually in an encapsulation or cyst.
One form of treatment for acute subdural hematomas is the performance of a craniotomy operation. This operation entails the removal (with eventual replacement) of a large portion of the skull, opening of the dura, and evacuation of the collection of blood. The craniotomy frequently necessitates the placement of a subdural drain, which comprises a tube extending through the hole created by the crainiotomy and into the subdural space for removing any additional accumulation of blood or fluid. The craniotomy is a highly invasive procedure that generally involves significant risk to the patient and an extended recovery period.
Since the subacute and chronic types of subdural hematomas primarily comprise collections of liquid, the treatment may range from the performance of a craniotomy to the use of a burr hole. The burr hole operation generally comprises boring in the skull a hole that is smaller than the portion of skull removed in a craniotomy. The burr hole generally has a diameter of about 14 to 18 mm. Through the burr hole, extensive washing of the subdural space may be carried out. Frequently, a drain needs to be left in place through the burr hole, with the end of the drain being in communication with the surface of the brain in order to allow for postoperative drainage of any further accumulations of fluid. Again, the patient is exposed to a fairly invasive procedure and a relatively long recovery period.
The aforementioned drains are typically used in combination with the application of negative pressure through the tube of the drain. The typical level of the negative pressure applied by the drains frequently causes further hemorrhage of the brain, especially if the end of the tube should come in contact with the surface of the brain. Further, recurrence of subdural hematomas and hygromas is quite common in chronic cases as the brain generally fails to expand to fill the enlarged subdural space created by the collection of fluid. If the subdural space remains enlarged after removal of the fluid, additional fluid tends to collect in the enlarged subdural space. The aforementioned treatment techniques do not actively contribute to re-expansion of the brain within the dura, and therefore do little to prevent the re-accumulation of fluid in the enlarged subdural space.
The subdural evacuating port system according to the present invention substantially departs from the conventional concepts and designs and methods of the prior art, and in so doing provides an apparatus and method primarily developed for the purpose of removing subdural fluid accumulations in a manner that is minimally invasive and promotes decompression, expansion, and recovery of the brain.